Measurements in both experimental animals and man indicate that dopamine (DA) is released in significant quantities into the bloodstream during periods of stress. The source of the DA is not known since DA constitutes only a small fraction (1-5%) of total peripheral catecholamine (CA). That peripheral DA is functionally important, however, cannot be doubted since a variety of DA-specific receptor sites in peripheral organs have been identified. In the present proposal, we wish to investigate the hypothesis that acute morphine administration releases DA in disproportionately increased amounts from the adrenal medulla because the sympathetic stimulation induced by morphine increases the ratio of DA to other CA in adrenal medullary storage granules. We will utilize fluorimetric assays, radioactive labelling of adrenal and plasma CA by 3H-tyrosine precursor and enzyme inhibition techniques to estimate turnover and release of DA and the beta-hydroxylated CA.